The present invention relates to dynamoelectric machines capable of operating either in a generator mode or in a motor mode and, more particularly, the present invention relates to dynamoelectric machines of the radial- and axial- gap-type.
Dynamoelectric machines, motors and generators, are generally of the radial magnetic gap type, being provided with an annular peripheral stator and a cylindrical rotor disposed internally of the stator. Electrical current supplied to the windings of the rotor or stator, or to the windings of both, generates electromagnetic fields in the rotor or in the stator, as the case may be. In electric motors, the electromagnetic fields react with each other or with magnetic fields created by permanent magnets to produce forces of attraction or repulsion between the rotor and the stator which in turn cause the rotor to rotate in unison with a shaft supporting the rotor. In electrical generators, the rotation of the rotor causes an electromotive force to be induced in the windings. In such dynamoelectric machines, the attraction and repulsion forces, and the induced electromotive forces, are created at the cylindrical magnetic interface or gap between the rotor and the stator.
Another type of dynamoelectric machine, often referred to as the axial gap type, is provided with a disc-shaped rotor keyed to a rotatable shaft. The stator or stators are axially arranged relative to the rotor such that the magnetic interface or gap, through which the attraction or repulsion forces of the magnetic fields are exerted and the variable magnetic fields inducing an electromotive force are created, respectively in motors and in generators, are axially or longitudinally aligned with respect to the housing and rotatable shaft of the dynamoelectric machine.
A third type of dynamoelectric machines, best represented by the structures disclosed in the above-mentioned U.S. Pat. Nos. 3,602,749 and 3,729,642 and also in U.S. Pat. Nos. 3,426,224 and 3,396,296, all issued to applicant, presents the combined advantage of both the radial gap and axial gap dynamoelectric machines. In such structures, a first stator is disposed within a hollow cylindrical rotor and a second stator, also cylindrical in shape, is disposed such as to surround the rotor. A double radial gap dynamoelectric machine is thus formed. In addition, end stators are provided on the lateral ends of the rotor so as to form an axial gap between the ends of the rotor and the magnetic field created by the end stators. An electric motor, or an electric generator, built according to such principle has a greater efficiency than conventional motors or generators, as a result of the greatly increased interreaction between a multitude of magnetic fields and electromagnetic fields.